E30 Fuel tank (expanded capacity)

[briansjacobs]

I had heard in the past about an optional expanded capacity fuel tank for the E30 M3, I have an E30 325 race car and I only get about 75 minutes before fuel starvation. I need to get to about 100 minutes.

Has any body heard of this fuel tank? any leads where to get one? The next option is a very costly fuel cell, If I do a fuel cell it will be a 24 Gallon which would get me to about 150 minutes

[jlevie]

What is the production date of your car. If before 9/87, it will have a 55 liter tank. Cars built after 9/87 have 63 liter tanks. It isn't difficult to swap in the later tank.

Either tank can benefit from "blowing out the tank' to slightly stretch it. I gained another gallon of capacity on the tank that's now in my Spec E30 this way. Care has to be exercised when doing this to avoid altering the overall shape of the tank and just enough pressure used to have the tank go "bong".

The other issue is to make sure that you can use all the fuel that is in the tank. For the early tank, a surge tank that holds about a gallon is the best solution. For the later tank fitting a second pump as a transfer pump is a good solution. If you can change the tuning, set the engine management system up for economy (~14:1) for enduros. The slight loss of performance costs less than the time lost in an extra fuel stop.

When I ran the 55 liter tank with a stock M20B25 (mandated by Spec E30 rules) I could get right at 90 minutes of race time out of the 55 liter tank before fuel starvation in corners became severe. I haven't yet run the new car in an enduro, but with my new set up (blown out 63 liter tank, secondary transfer pump mod) I should be able to run close to 110 minutes.

[briansjacobs]

thanks for the input, Im at 2.L so I eat some fuel!

[Jean]

Instead of swapping a tank, try adding a small exp. tank for the fuel between the two pumps?

[craz azn]

You need one of these :D

http://www.r3vlimited.com/board/showthread.php?t=130319

[Ceeker]

You need one of these :D

http://www.r3vlimited.com/board/showthread.php?t=130319

Will u throw in the foot? (Grin)

[george graves]

Pro tip: Use large fuel lines. ;)

[RangerGress]

thanks for the input, Im at 2.L so I eat some fuel!

Not sure what 2.L was, but I burn about a gal every 7.5min. That works out to 13.3gal for 100min. I've seen early and late model SpecE30's with good condition fuel tanks race just fine until after the Reserve light came on. If you are burning fuel at the same rate I am, you're primary problem is just the same 20yr old fuel system hiccups that most of us have. Just put in a new tank and hoses, or better yet, swap out your tank with a nice late model tank, and you'll probably be fine. And if there's some laps under FCY you'll even have a nice margin.

Jim Levie has a write up on cleaning & sealing his tank instead of putting in a new one.

There's an Altlanta based SpecE30 type by the name of Jim Robinson that put a fuel cell into his car. Was expensive, but he sure can refuel in a hurry. I don't think that he would recommend that others do it. Apparently it was a pita.

[briansjacobs]

Sorry im 2.8L, at Homestead I burned 9 gal in 60 minutes and 30 of those minutes were with a stident driving about 2 seconds a lap slower than me. That equates to a gal every 5 minutes (ISH), I am planning to put my pick up in a tank in the fuel tank with a pump filling it directly, that should get me to the bottom of the tank, but then that only gives me another 20 minutes of run time. Starting to sound like a fuel cell is the way to go anyway I slice it.

I actually just replaced the tank with an aftermarket replacement tank not knowing there was a difference. Both my fuel pumps are working properly.

[jlevie]

A properly installed fuel cell is an expensive proposition and requires some pretty radical mods to the car. Unless you get a custom cell built you have to mount the tank where the spare tire well is. That's in the crush zone and there's no way I'd want a fuel cell there unless I was going to do a major reinforcement of that area. Plus placing fuel there will increase the polar moment and result is a varying front to back weight balance as fuel is burned. The stock tank, located just in front of the rear axle is in a very good location (protected and as fuel is burned the balance change is minimal).

What I'd do, given that fuel consumption rate and not being constrained by rules, would be to start with the 63L tank. I'd fit the tank with two in-tank transfer pumps and have them feed a 2-5 gallon cell mounted between the shock towers. Overflow from the top of cell would return to the tank at the siphon inlet. The bottom of the tank would feed a high pressure pump and fuel returning from the engine would feed into the top of the cell. That will give you better than 18 gallons of fuel and allow just about all of it to be used. The only required car mods would then be a solid bulkhead over the rear seat back and parcel shelf.

[blueapplesoda]

A properly installed fuel cell is an expensive proposition and requires some pretty radical mods to the car. Unless you get a custom cell built you have to mount the tank where the spare tire well is. That's in the crush zone and there's no way I'd want a fuel cell there unless I was going to do a major reinforcement of that area. Plus placing fuel there will increase the polar moment and result is a varying front to back weight balance as fuel is burned. The stock tank, located just in front of the rear axle is in a very good location (protected and as fuel is burned the balance change is minimal).

What I'd do, given that fuel consumption rate and not being constrained by rules, would be to start with the 63L tank. I'd fit the tank with two in-tank transfer pumps and have them feed a 2-5 gallon cell mounted between the shock towers. Overflow from the top of cell would return to the tank at the siphon inlet. The bottom of the tank would feed a high pressure pump and fuel returning from the engine would feed into the top of the cell. That will give you better than 18 gallons of fuel and allow just about all of it to be used. The only required car mods would then be a solid bulkhead over the rear seat back and parcel shelf.

I like this idea. guess its time to get fabbin. Ive got starvation issues at half tank in big rights. and I've been wanting to do something about it but always ended up just adding more fuel since i don't use this car in competition.

[jlevie]

I like this idea. guess its time to get fabbin. Ive got starvation issues at half tank in big rights. and I've been wanting to do something about it but always ended up just adding more fuel since i don't use this car in competition.

That would be a sign of fuel not properly being equalized between the sides of the tank. The cause varies according to which tank you have. The early tank uses a crossover tube to equalize and a lift pump in the tank to feed the high pressure pump. Rust in the tank can clog the cross over tube and/or a weak lift pump may be preset. Either can cause premature starvation in right hand turns. When everything is working properly and the tank has no rust you should be able to go down to the point that the fuel warning light is on or about to come on w/o encountering starvation.

The later tank uses a siphon operated by returning fuel. A weak pump, clogged filter, or obstructed return line can result in the right side of the tank being starved for fuel.

Before going to a more aggressive solution, find and fix the current problem. I.E., treat the disease, not the symptoms.

[briansjacobs]

Jlevie, I was thinking about an aux tank mounted between the rear shock towers also. Yes a fuel cell with the proper reinforcement will be about $3000 for a 24G cell. As I just put a new tank in the car I know it is not a rust issue, but I will check the pumps and return lines as suggested. I'll tell you what though an aux tank wont save alot of money over a cell, but placement will be mutch better.

[blueapplesoda]

I got the later style tank. I will check the return line, thanks for the tip.

Still gonna fab up the aux though.

[briansjacobs]

blueapple-after hearing all these great things about your turbo kit im starting to regret those 10.5:1 pistons I put in my 2.8 build.